diff --git a/datamodel/low/base/schema_proxy.go b/datamodel/low/base/schema_proxy.go
index 15b225d..d715cab 100644
--- a/datamodel/low/base/schema_proxy.go
+++ b/datamodel/low/base/schema_proxy.go
@@ -4,6 +4,7 @@
 package base
 
 import (
+	"crypto/sha256"
 	"github.com/pb33f/libopenapi/datamodel/low"
 	"github.com/pb33f/libopenapi/index"
 	"github.com/pb33f/libopenapi/utils"
@@ -120,6 +121,13 @@ func (sp *SchemaProxy) Hash() [32]byte {
 	if sp.rendered != nil {
 		return sp.rendered.Hash()
 	} else {
-		return sp.Schema().Hash()
+		if !sp.isReference {
+			// only resolve this proxy if it's not a ref.
+			sch := sp.Schema()
+			sp.rendered = sch
+			return sch.Hash()
+		}
 	}
+	// hash reference value only, do not resolve!
+	return sha256.Sum256([]byte(sp.referenceLookup))
 }
diff --git a/datamodel/low/v3/components.go b/datamodel/low/v3/components.go
index 31e878b..9f7fd55 100644
--- a/datamodel/low/v3/components.go
+++ b/datamodel/low/v3/components.go
@@ -39,7 +39,6 @@ func (co *Components) FindExtension(ext string) *low.ValueReference[any] {
 // FindSchema attempts to locate a SchemaProxy from 'schemas' with a specific name
 func (co *Components) FindSchema(schema string) *low.ValueReference[*base.SchemaProxy] {
 	return low.FindItemInMap[*base.SchemaProxy](schema, co.Schemas.Value)
-
 }
 
 // FindResponse attempts to locate a Response from 'responses' with a specific name
@@ -169,8 +168,22 @@ func extractComponentValues[T low.Buildable[N], N any](label string, root *yaml.
 	eChan := make(chan error)
 	var buildComponent = func(label *yaml.Node, value *yaml.Node, c chan componentBuildResult[T], ec chan<- error) {
 		var n T = new(N)
+
+		// if this is a reference, extract it (although components with references is an antipattern)
+		// If you're building components as references... pls... stop, this code should not need to be here.
+		// TODO: check circular crazy on this. It may explode
+		var err error
+		if h, _, _ := utils.IsNodeRefValue(value); h && label.Value != SchemasLabel {
+			value, err = low.LocateRefNode(value, idx)
+		}
+		if err != nil {
+			ec <- err
+			return
+		}
+
+		// build.
 		_ = low.BuildModel(value, n)
-		err := n.Build(value, idx)
+		err = n.Build(value, idx)
 		if err != nil {
 			ec <- err
 			return
diff --git a/what-changed/model/comparison_functions.go b/what-changed/model/comparison_functions.go
index 7325559..529525f 100644
--- a/what-changed/model/comparison_functions.go
+++ b/what-changed/model/comparison_functions.go
@@ -224,7 +224,9 @@ func CheckMapForChanges[T any, R any](expLeft, expRight map[low.KeyReference[str
 			return
 		}
 		// run comparison.
+		chLock.Lock()
 		expChanges[k] = compareFunc(p[k].Value, h[k].Value)
+		chLock.Unlock()
 		doneChan <- true
 	}
 
diff --git a/what-changed/model/components.go b/what-changed/model/components.go
index d49b8a1..b3f050f 100644
--- a/what-changed/model/components.go
+++ b/what-changed/model/components.go
@@ -5,8 +5,8 @@ package model
 
 import (
 	"github.com/pb33f/libopenapi/datamodel/low"
-	v2 "github.com/pb33f/libopenapi/datamodel/low/v2"
-	v3 "github.com/pb33f/libopenapi/datamodel/low/v3"
+	"github.com/pb33f/libopenapi/datamodel/low/v2"
+	"github.com/pb33f/libopenapi/datamodel/low/v3"
 	"reflect"
 )
 
@@ -77,55 +77,55 @@ func CompareComponents(l, r any) *ComponentsChanges {
 		comparisons := 0
 
 		// run as fast as we can, thread all the things.
-		if !lComponents.Schemas.IsEmpty() || rComponents.Schemas.IsEmpty() {
+		if !lComponents.Schemas.IsEmpty() || !rComponents.Schemas.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Schemas.Value, rComponents.Schemas.Value,
 				&changes, v3.SchemasLabel, CompareSchemas, doneChan)
 		}
 
-		if !lComponents.Responses.IsEmpty() || rComponents.Responses.IsEmpty() {
+		if !lComponents.Responses.IsEmpty() || !rComponents.Responses.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Responses.Value, rComponents.Responses.Value,
 				&changes, v3.ResponsesLabel, CompareResponseV3, doneChan)
 		}
 
-		if !lComponents.Parameters.IsEmpty() || rComponents.Parameters.IsEmpty() {
+		if !lComponents.Parameters.IsEmpty() || !rComponents.Parameters.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Parameters.Value, rComponents.Parameters.Value,
 				&changes, v3.ParametersLabel, CompareParametersV3, doneChan)
 		}
 
-		if !lComponents.Examples.IsEmpty() || rComponents.Examples.IsEmpty() {
+		if !lComponents.Examples.IsEmpty() || !rComponents.Examples.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Examples.Value, rComponents.Examples.Value,
 				&changes, v3.ExamplesLabel, CompareExamples, doneChan)
 		}
 
-		if !lComponents.RequestBodies.IsEmpty() || rComponents.RequestBodies.IsEmpty() {
+		if !lComponents.RequestBodies.IsEmpty() || !rComponents.RequestBodies.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.RequestBodies.Value, rComponents.RequestBodies.Value,
 				&changes, v3.RequestBodiesLabel, CompareRequestBodies, doneChan)
 		}
 
-		if !lComponents.Headers.IsEmpty() || rComponents.Headers.IsEmpty() {
+		if !lComponents.Headers.IsEmpty() || !rComponents.Headers.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Headers.Value, rComponents.Headers.Value,
 				&changes, v3.HeadersLabel, CompareHeadersV3, doneChan)
 		}
 
-		if !lComponents.SecuritySchemes.IsEmpty() || rComponents.SecuritySchemes.IsEmpty() {
+		if !lComponents.SecuritySchemes.IsEmpty() || !rComponents.SecuritySchemes.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.SecuritySchemes.Value, rComponents.SecuritySchemes.Value,
 				&changes, v3.SecuritySchemesLabel, CompareSecuritySchemesV3, doneChan)
 		}
 
-		if !lComponents.Links.IsEmpty() || rComponents.Links.IsEmpty() {
+		if !lComponents.Links.IsEmpty() || !rComponents.Links.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Links.Value, rComponents.Links.Value,
 				&changes, v3.LinksLabel, CompareLinks, doneChan)
 		}
 
-		if !lComponents.Callbacks.IsEmpty() || rComponents.Callbacks.IsEmpty() {
+		if !lComponents.Callbacks.IsEmpty() || !rComponents.Callbacks.IsEmpty() {
 			comparisons++
 			go runComparison(lComponents.Callbacks.Value, rComponents.Callbacks.Value,
 				&changes, v3.CallbacksLabel, CompareCallback, doneChan)
@@ -246,9 +246,6 @@ func (c *ComponentsChanges) TotalBreakingChanges() int {
 	for k := range c.ParameterChanges {
 		v += c.ParameterChanges[k].TotalBreakingChanges()
 	}
-	for k := range c.ExamplesChanges {
-		v += c.ExamplesChanges[k].TotalBreakingChanges()
-	}
 	for k := range c.RequestBodyChanges {
 		v += c.RequestBodyChanges[k].TotalBreakingChanges()
 	}
@@ -264,8 +261,5 @@ func (c *ComponentsChanges) TotalBreakingChanges() int {
 	for k := range c.CallbackChanges {
 		v += c.CallbackChanges[k].TotalBreakingChanges()
 	}
-	if c.ExtensionChanges != nil {
-		v += c.ExtensionChanges.TotalBreakingChanges()
-	}
 	return v
 }
diff --git a/what-changed/model/components_test.go b/what-changed/model/components_test.go
index 7d74069..55a0b5a 100644
--- a/what-changed/model/components_test.go
+++ b/what-changed/model/components_test.go
@@ -5,8 +5,9 @@ package model
 
 import (
 	"github.com/pb33f/libopenapi/datamodel/low"
-	v2 "github.com/pb33f/libopenapi/datamodel/low/v2"
-	v3low "github.com/pb33f/libopenapi/datamodel/low/v3"
+	"github.com/pb33f/libopenapi/datamodel/low/v2"
+	"github.com/pb33f/libopenapi/datamodel/low/v3"
+	"github.com/pb33f/libopenapi/index"
 	"github.com/stretchr/testify/assert"
 	"gopkg.in/yaml.v3"
 	"testing"
@@ -227,7 +228,7 @@ param3:
 	assert.Equal(t, Modified, extChanges.ParameterChanges["param1"].Changes[0].ChangeType)
 	assert.Equal(t, "WIDE AWAKE", extChanges.ParameterChanges["param1"].Changes[0].New)
 	assert.Equal(t, "KINDA SNOOZ", extChanges.ParameterChanges["param3"].Changes[0].New)
-	assert.Equal(t, v3low.NameLabel, extChanges.ParameterChanges["param1"].Changes[0].Property)
+	assert.Equal(t, v3.NameLabel, extChanges.ParameterChanges["param1"].Changes[0].Property)
 
 }
 
@@ -366,7 +367,7 @@ resp2:
 	assert.Equal(t, 1, extChanges.TotalChanges())
 	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
 	assert.Equal(t, 1, extChanges.ResponsesChanges["resp2"].TotalChanges())
-	assert.Equal(t, v3low.DescriptionLabel, extChanges.ResponsesChanges["resp2"].Changes[0].Property)
+	assert.Equal(t, v3.DescriptionLabel, extChanges.ResponsesChanges["resp2"].Changes[0].Property)
 }
 
 func TestCompareComponents_Swagger_Responses_Added(t *testing.T) {
@@ -499,5 +500,856 @@ scheme2:
 	assert.Equal(t, 1, extChanges.TotalChanges())
 	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
 	assert.Equal(t, 1, extChanges.SecuritySchemeChanges["scheme2"].TotalChanges())
-	assert.Equal(t, v3low.DescriptionLabel, extChanges.SecuritySchemeChanges["scheme2"].Changes[0].Property)
+	assert.Equal(t, v3.DescriptionLabel, extChanges.SecuritySchemeChanges["scheme2"].Changes[0].Property)
+}
+
+func TestCompareComponents_OpenAPI_Schemas_Equal(t *testing.T) {
+
+	left := `
+schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.`
+
+	right := `schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Schemas_Refs_FullBuild(t *testing.T) {
+
+	left := `components:
+  schemas:
+    coffee:
+      description: tasty
+    tv:
+      $ref: '#/components/schemas/coffee'`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+
+	idx := index.NewSpecIndex(&lNode)
+
+	_ = lDoc.Build(lNode.Content[0], idx)
+	_ = rDoc.Build(rNode.Content[0], idx)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Schemas_Modify(t *testing.T) {
+
+	left := `
+schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.`
+
+	right := `schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring, except when it is sci-fi`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+	assert.Equal(t, 1, extChanges.SchemaChanges["tv"].TotalChanges())
+	assert.Equal(t, v3.DescriptionLabel, extChanges.SchemaChanges["tv"].Changes[0].Property)
+}
+
+func TestCompareComponents_OpenAPI_Schemas_Add(t *testing.T) {
+
+	left := `
+schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.`
+
+	right := `schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.
+  herbs:
+    description: need a massive slowdown`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "herbs", extChanges.Changes[0].New)
+}
+
+func TestCompareComponents_OpenAPI_Schemas_Remove(t *testing.T) {
+
+	left := `
+schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.`
+
+	right := `schemas:
+  coffee:
+    description: tasty
+  tv:
+    description: mostly boring.
+  herbs:
+    description: need a massive slowdown`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&rDoc, &lDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 1, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "herbs", extChanges.Changes[0].Original)
+}
+
+func TestCompareComponents_OpenAPI_Responses_Equal(t *testing.T) {
+
+	left := `
+responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Responses_FullBuild(t *testing.T) {
+	left := `components:
+  responses:
+    coffee:
+      description: tasty
+    tv:
+      $ref: '#/components/responses/coffee'`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+
+	idx := index.NewSpecIndex(&lNode)
+
+	_ = lDoc.Build(lNode.Content[0], idx)
+	_ = rDoc.Build(rNode.Content[0], idx)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Responses_FullBuild_IdenticalRef(t *testing.T) {
+	left := `components:
+  responses:
+    coffee:
+      description: tasty
+    tv:
+      $ref: '#/components/responses/coffee'`
+
+	right := `components:
+  responses:
+    coffee:
+      $ref: '#/components/responses/tv'
+    tv:
+      description: tasty`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+
+	idx := index.NewSpecIndex(&lNode)
+	idx2 := index.NewSpecIndex(&rNode)
+
+	_ = lDoc.Build(lNode.Content[0], idx)
+	_ = rDoc.Build(rNode.Content[0], idx2)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Responses_Modify(t *testing.T) {
+
+	left := `responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please`
+
+	right := `responses:
+  niceResponse:
+    description: hello my matey
+  badResponse:
+    description: go away please, now!`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&rDoc, &lDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_Responses_Add(t *testing.T) {
+
+	left := `responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please!`
+
+	right := `responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please!
+  indifferent:
+    description: stay, or go, who cares?`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "indifferent", extChanges.Changes[0].New)
+}
+
+func TestCompareComponents_OpenAPI_Responses_Remove(t *testing.T) {
+
+	left := `responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please!`
+
+	right := `responses:
+  niceResponse:
+    description: hello
+  badResponse:
+    description: go away please!
+  indifferent:
+    description: stay, or go, who cares?`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&rDoc, &lDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 1, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "indifferent", extChanges.Changes[0].Original)
+}
+
+func TestCompareComponents_OpenAPI_Parameters_Equal(t *testing.T) {
+
+	left := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Parameters_Modified(t *testing.T) {
+
+	left := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param`
+
+	right := `parameters:
+  param1:
+    name: a parameter modified
+  param2:
+    name: another param but modified`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 2, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_Parameters_Added(t *testing.T) {
+
+	left := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param`
+
+	right := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param
+  param3:
+    name: do you like code?`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "param3", extChanges.Changes[0].New)
+}
+
+func TestCompareComponents_OpenAPI_Parameters_Removed(t *testing.T) {
+
+	left := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param`
+
+	right := `parameters:
+  param1:
+    name: a parameter
+  param2:
+    name: another param
+  param3:
+    name: do you like code?`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&rDoc, &lDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
+	assert.Equal(t, 1, extChanges.TotalBreakingChanges())
+	assert.Equal(t, "param3", extChanges.Changes[0].Original)
+}
+
+func TestCompareComponents_OpenAPI_Examples_Equal(t *testing.T) {
+
+	left := `examples:
+  example1:
+    description: an example
+  example2:
+    description: another example`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Examples_Modified(t *testing.T) {
+
+	left := `examples:
+  example1:
+    description: an example
+  example2:
+    description: another example`
+
+	right := `examples:
+  example1:
+    description: change me
+  example2:
+    description: grow me`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_RequestBodies_Equal(t *testing.T) {
+
+	left := `requestBodies:
+  body1:
+    description: a request
+  body2:
+    description: another request`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_RequestBodies_Modified(t *testing.T) {
+
+	left := `requestBodies:
+  body1:
+    description: a request
+  body2:
+    description: another request`
+
+	right := `requestBodies:
+  body1:
+    description: a request but changed
+  body2:
+    description: another request, also changed`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_Headers_Equal(t *testing.T) {
+
+	left := `headers:
+  header1:
+    description: a header
+  header2:
+    description: another header`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Headers_Modified(t *testing.T) {
+
+	left := `headers:
+  header1:
+    description: a header
+  header2:
+    description: another header`
+
+	right := `headers:
+  header1:
+    description: a header but different
+  header2:
+    description: another header, also different`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 0, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_SecuritySchemes_Equal(t *testing.T) {
+
+	left := `securitySchemes:
+  scheme1:
+    description: a scheme
+  scheme2:
+    description: another scheme`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Links_Equal(t *testing.T) {
+
+	left := `links:
+  link1:
+    operationId: link1
+  link2:
+    operationId: link2`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Links_Modified(t *testing.T) {
+
+	left := `links:
+  link1:
+    operationId: link1
+  link2:
+    operationId: link2`
+
+	right := `links:
+  link1:
+    operationId: somethingFresh
+  link2:
+    operationId: somethingNew`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 2, extChanges.TotalChanges())
+	assert.Equal(t, 2, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_Callbacks_Equal(t *testing.T) {
+
+	left := `callbacks:
+  link1:
+    url: https://pb33f.io
+  link2:
+    url: https://pb33f.io`
+
+	right := left
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Nil(t, extChanges)
+}
+
+func TestCompareComponents_OpenAPI_Callbacks_Modified(t *testing.T) {
+
+	left := `callbacks:
+  link1:
+    '{$request.query.queryUrl}':
+      post:
+        description: a nice callback
+  link2:
+    '{$pizza.cake.burgers}':
+      post:
+        description: pizza and cake, and burgers.`
+
+	right := `callbacks:
+  link1:
+    '{$request.query.queryUrl}':
+      post:
+        description: a nice callback, but changed
+  link2:
+    '{$pizza.cake.burgers}':
+      get:
+        description: pizza and cake, and burgers, and ketchup.`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 3, extChanges.TotalChanges())
+	assert.Equal(t, 1, extChanges.TotalBreakingChanges())
+}
+
+func TestCompareComponents_OpenAPI_Extensions_Modified(t *testing.T) {
+
+	left := `x-components: are done"`
+
+	right := `x-components: I hope`
+
+	var lNode, rNode yaml.Node
+	_ = yaml.Unmarshal([]byte(left), &lNode)
+	_ = yaml.Unmarshal([]byte(right), &rNode)
+
+	// create low level objects
+	var lDoc v3.Components
+	var rDoc v3.Components
+	_ = low.BuildModel(lNode.Content[0], &lDoc)
+	_ = low.BuildModel(rNode.Content[0], &rDoc)
+	_ = lDoc.Build(lNode.Content[0], nil)
+	_ = rDoc.Build(rNode.Content[0], nil)
+
+	// compare.
+	extChanges := CompareComponents(&lDoc, &rDoc)
+	assert.Equal(t, 1, extChanges.TotalChanges())
 }
diff --git a/what-changed/model/schema_test.go b/what-changed/model/schema_test.go
index 6bc6300..03be331 100644
--- a/what-changed/model/schema_test.go
+++ b/what-changed/model/schema_test.go
@@ -199,17 +199,21 @@ func TestCompareSchemas_RefIgnore(t *testing.T) {
 func TestCompareSchemas_RefChanged(t *testing.T) {
 	left := `components:
   schemas:
-    Yo:
+    Woah:
       type: int
+    Yo:
+      type: string
     OK:
-      $ref: '#/components/schemas/No'`
+      $ref: '#/components/schemas/Woah'`
 
 	right := `components:
   schemas:
-    Yo:
+    Woah:
       type: int
+    Yo:
+      type: string
     OK:
-      $ref: '#/components/schemas/Woah'`
+      $ref: '#/components/schemas/Yo'`
 
 	leftDoc, rightDoc := test_BuildDoc(left, right)
 
@@ -221,7 +225,7 @@ func TestCompareSchemas_RefChanged(t *testing.T) {
 	assert.NotNil(t, changes)
 	assert.Len(t, changes.Changes, 1)
 	assert.Equal(t, Modified, changes.Changes[0].ChangeType)
-	assert.Equal(t, "#/components/schemas/Woah", changes.Changes[0].New)
+	assert.Equal(t, "string", changes.Changes[0].New)
 }
 
 func TestCompareSchemas_RefToInline(t *testing.T) {
@@ -230,7 +234,7 @@ func TestCompareSchemas_RefToInline(t *testing.T) {
     Yo:
       type: int
     OK:
-      $ref: '#/components/schemas/No'`
+      $ref: '#/components/schemas/Yo'`
 
 	right := `components:
   schemas:
@@ -249,8 +253,8 @@ func TestCompareSchemas_RefToInline(t *testing.T) {
 	assert.NotNil(t, changes)
 	assert.Len(t, changes.Changes, 1)
 	assert.Equal(t, Modified, changes.Changes[0].ChangeType)
-	assert.Equal(t, v3.RefLabel, changes.Changes[0].Property)
-	assert.Equal(t, "#/components/schemas/No", changes.Changes[0].Original)
+	assert.Equal(t, v3.TypeLabel, changes.Changes[0].Property)
+	assert.Equal(t, "int", changes.Changes[0].Original)
 
 }
 
@@ -260,7 +264,7 @@ func TestCompareSchemas_InlineToRef(t *testing.T) {
     Yo:
       type: int
     OK:
-      $ref: '#/components/schemas/No'`
+      $ref: '#/components/schemas/Yo'`
 
 	right := `components:
   schemas:
@@ -279,8 +283,8 @@ func TestCompareSchemas_InlineToRef(t *testing.T) {
 	assert.NotNil(t, changes)
 	assert.Len(t, changes.Changes, 1)
 	assert.Equal(t, Modified, changes.Changes[0].ChangeType)
-	assert.Equal(t, v3.RefLabel, changes.Changes[0].Property)
-	assert.Equal(t, "#/components/schemas/No", changes.Changes[0].New)
+	assert.Equal(t, v3.TypeLabel, changes.Changes[0].Property)
+	assert.Equal(t, "int", changes.Changes[0].New)
 
 }